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G. H. HADFIELD AND A.'E. BAWTREE. PROCESS FOR TREATING POROUS VESSELS.

APPLICATION FILED OCT. 15. 1918.

Patented June 10, 1919.

' 314w who .BAWTREE,

GEORGE HUG-H HADFIELD, or MITCHAM, AND ALFRED EDWIN newsman, or surrou,

. ENGLAND.

PROCESS FOR TREATING POROUS VESSELS.

To all whom it may concern:

Be it known that we, GEORGE HUGH HAD- FIELD, a subject of the King ofGreat Britain, residing at Hadfields (Merton) Limited, Western Road,Mitcham, Surrey, En land, varnish manufacturer, and ALFRED DWIN asubject of the King of Qrreat Britain, residing at 7 Manor Park road,Sutton, Surrey, England, have invented a new and useful Improved Processfor Treating Porous Vessels, of which the following is a specification.

This invention relates to a process for treating the inner walls ofvessels composed or more or less porous material with a suitable fluidwhich dries or sets after a period. The process is particularlyapplicable to the treatment of vessels composed! partly or wholly ofpaper or cardboard.

Various difliculties arise in making a thoroughly impervious vessel.Thus the interior portions of the vessel do not usually consist ofperfectly continuous surfaces but are broken up by pits or fissures dueto the method of manufacture. For example, one

form of cylindrical package has a spiral crack or groove around itsinterior where two strips of cardboard butt. If the interior surfaces ofsuch vessels are merely flowed over or lightly brushed over with a fluidcomposition, such composition merely bridges across the fissures orgrooves and upon drying cracks leaving them quite unprotected.

In the accompanying drawing,

Figure 1 show a vertical section ofa vessel of porous materialconstructed and treated according to our invention.

Figs. 2, 3 and 4 illustrate the steps of one way of carrying out ourinvention.

Fig. 2 shows how a vessel of porous material formed by spirally windingpaper or the like has its opposite ends dipped in proofing material.

Fig. 3 illustrates how the vessel treated in the manner indicated inFig. 2 has a bottom applied to one end and a ring, formin part of theclosure, applied to the other en Fig. 4shows the next step in theprocess wherein the interior of the vessel and the joints, proofingmaterial. V

Fig. 5 illustrates a machine which may be employed for rotatingthevessel duringthe process of coating or proofing the interior thereof.

Specification of Letters Patent.

fissures, etc., are'coated and filled with Patented June 10, 1919.

Application flledoctober 15, 1918. Serial No. 258,307.

According to this invention a quantity of a protective fluid orcomposition which has little or no penetrative power into the substanceof the vessel treated, is placed in the vessel and is then spread overevery detail of the contour of the interior surface by the action ofcentrifugal force. The vessel must be rotated at such a speed that ifits axis be horizontal centrifugal force shall at least counteracttheforce of gravity in portions of surface which are for the time beingvertically above the axis of rotation as in this case the coatingmaterial will be driven so strongly into the imperfections in thesurface as to cause the coating to accurately follow every detail of thecontour of the surface. At the same time it is evident that the axis of.rotation need not necessarily be truly horizontal but may be inclined toany convenient angle.

If the rotation be at too low a speed the coating fluid or compositionwould flow by gravity over the entire surface in the manner alreadyknown in such operations as in the pitching of barrels, but such coatingwould not be reliable. It is important that the fluid should accuratelyfollow the surfaces of the imperfections in the walls of the vessel inthe manner described. It is also important that this penetration ofimperfections should not be confounded with the soaking in by 'of fluidin the vessel; if a small quantity of fluid be employed, rotation ismerely continued till it is evenly distributed; if a larger amount beused, rotation must be continued till it has become set and no longerfluld. In this latter case there is no limit to the duck ness of comosition which can be spread upon the surface at a single operation.

I The process may be carried out with the aid of any-mown mechanism forcausing the necessary rotation of the vessel which should combine thenecessary speed with great accuracy of rotation. This last point is oneof great importance If, for example,

a container is receiving a coating of fluid one sixteenth of an inchthick, but one side is one sixteenth ofan inch farther from the centerof rotation than the other, this side will receive the whole of thesupply of coating material except such small quantity as may adhere tothe portions nearer to the center of rotation b the action of capillaryattraction.

The fluid or composition employed in the process depends upon the use towhich the vessels are to be put and the composition forms no part ofthis invention as the use of colloids such as glue and gelatin mixedwith hardening agents are known for this purpose as are also variouswaxes and the like and compositions consisting of rosin, linseed oildriers and turpentine, which will set hard or nearlv so when cold.

With some vessels and especially when a small quantity of fluid isplaced in the vessel it is necessary in order to produce a satisfactoryresult to subject the vessel to a prelimina treatment which has for itsobject the efliclent sealin of the joints between the ends and sides 0the vessel. To perform this operation we treat one or both of thesurfaces to be united with a composition possessing similar propertiesto that which we use for rendering the main portion of the surface ofthe vessel impervious and make the joints while such composition isstill in a more or less soft state. By this means any small fissures orimperfections occurririg in the operation of joining the portions 0 thevessel together are closed whereas if the coating of composition hadbeen allowed to become hard before making the joints, there would be thesame possibility of leakage as exists when the portions of a tincanister are merely bent together.

The following are specific examples of applications of our invention 1.A canister has a tin bottom and for its top a tin ring into which fits alever lid, the sides being composed of layers of paper. It is desired torender such a vessel suitable for containin a paint the ingredients ofwhich include oi and turpentine spirit. A suitable protectingcomposition would be a 10% solution of gelatin, the cardboard havingbeen previously treated with a hardening agent such as a saturatedsolution of alum. 'Each end of the cardboard tube which is to form thesides of the vessel is first by any suitable mechanism coated at theedges of the ends and to a short distance along each end of the interiorsurface. While the comosition is still wet the tin ends are spun on 1nthe ordinary manner. 0

The canister is laced in a suitable chuck and a quantity 0 the coatingcomposition poured in; the chuck is then revolved at a sufiiciently highspeed to produce the phenomenon of the counteraction of gravitation bycentrifugal force if the axis of rotation be horizontal in the mannerabove referred to. This preliminary treatment of the end of the vesselbefore spinning on tin ends may however be dispensed with if suflicientcomposition is employed.

2. A canister similar to that employed in example No. 1 is treated as inthat example so far as placing. the tin bottom and the tin ring isconcerned. It is now placed in a chuck and supplied with its quantum ofcomposition, by means of a brush charged with the coating fluid: acoating is thus distributed over the surface to'be proofed, eitherbefore or while the vessel is rotating. Rotation is then continued for asufiicient time and at a suflicient speed to produce the close fittingfilm secured by the action of centrifugal force.

3. A tube composed wholly of cardboard and provided with a cardboardshut over lid is to be used for holdin adhesive composed of dextrin andwater. he coating composition to be employed consists or rosin, 3 parts,linseed oil containing 1% of dissolved litharge 1 part and turpentine 1part and is of such a consistency as to be barely fluid when cold.

The bottom cap is first'placed upon a revolving support and a littlehols composltion poured into it. Centrifugal force dis tributes thecomposition over the bottom and up the sides of the cap. n

The cardboard tube is then pressed into the cap, a supply of meltedcomposition is poured in, the mouth'of the tube is closed with a conicalstopper and the tube rapidly rotated until the composition is firstevenly distributed and then sets, partly by cooling and partly by theabsorption by the porous walls of the spirit and oil which it contains.

Referring again to the accompanying drawings, we have illustrated inFig. 5 a machine which may be employed for rotating the vessel duringthe proofing process. As there shown the container A is gripped by thejaws B of a self-centering chuck C,

attached to a shaft or spindle D, turning in bearings E, mounted in anordinary lathe head F. The shaft or spindle is provided with-a pulley G,to which power may be applied for rotating it. Any other suitablemachines for this purpose may, however, be employed.

. Referring to Fig. 1, we have shown a ver-.

tical section of a vessel or containertreated in accordance with ourimprovements; a indicates the body of the container, which in thisinstance is made of spirally wound plied to the upper end of thecontainer, its peripheral portion d being bent around the end of thebody a. This form of container is well known and is used by us forpurposes of illustration only, it being understood that our improvementsmay be applied to containers of other kinds. The body porpreferablytreated in the same way to re-- ceive an annular coating w. (The productof this stage of manufacture is represented in Fig. 2.) The next step inthepreferred process is to apply the bottom 0 and the top ring 03, inthe manner indicated in Fig.3. The purpose of applying the roofingmaterial m, w is to insure the t osing of the joints at both top andbottom when the vessel is rotated in the manner before described.

Without such preliminary treatment there is liability of the joints notbeing completely sealed unless the centrifugal treatment is continuedfor a considerable time.

Fig. 4 illustrates the completed v'essel after the proofing material hasbeen applied centrifugally in the manner hereinbefore explained. Thisproofing material, which is indicated at 1, it will be observed,completely covers the interior of the paper or porous portions of thevessel, and it will also be observed that the material I enters thegrooves b, as indicated at a.

It is made to so enter the grooves by the centrifugal action beforeexplained. Without such treatment the proofing material would merelybridge the grooves and would be liable to crack or open along thegrooves,-and thus produce leakage. It will also be observed that by thecentrifugal action mentioned the joint of the bottom 0 with the body ofthe container is completely closed, the proofing material 3 uniting withthe material an to close the joint and thus prevent any leakage thatmight occur unless special provision was made to prevent it.

As before specified, after the body of the vessel is prepared in themanner indicated in Fig. 3, it is supplied with a suitable amount ofproofing material and is then held by rotating mechanism in the mannerindicated in Fig. 5 so as to rotate'about a horizontal axis with greataccuracy for the reasons before specified.

It will be understood that a suitable closure or lid may be applied tothe ring 03. It will also be understood that we do not intend to limitour invention to the preliminary treatment before specified as it is notin all cases necessary.

We are aware that it has been proposed to impart rotation to cartridgeswhile their interiors are being varnished with a brush but it is clearthat in the treatment of these articles the action of centrifugal forceis not made use of. Such force, owing to its great power of uniformlyspreading a fluid would cause the varnish to flow over the portion ofthe tube which has at great pains been cleaned with a wiper for thereception of the bullet.

What we claim is A process of applying a liquid coating compositioncapable of hardening, to the interior surface of a receptacle of whichthe inner wall is made of a somewhat pervious material having cracks orfissures therein, such process comprising rotating the receptacle, withsuch coating composition therein, at such a rapid rate of speed that thesaid coating composition is spread out in the form of a coating on theinterior of said receptacle, and forced into said cracks and fissures,substantially as specified.

' In testimony that we claim the foregoing as our invention, we havesigned our names this 19th day of September, 1918.

GEORGE HUGH HADFIELD. ALFRED EDWIN BAWTREE.

